Is Reality Just A Hallucination In The Brain? - Anil Seth

1. 0:00 – 0:28

   Intro

   1. ASAnil Seth0:00

      Most of us, at one point or another in our lives, have wondered, "Who am I really? Why am I me and not someone else? Where was I before I was born? What will happen after I die? Am I the same person from one year to the next?" These are very personal questions. When we take the self to be not the thing that does the perceiving, but an aspect of this flow of conscious experience that requires explanation itself, then I think we're making progress. (graphics whoosh)

   2. CWChris Williamson0:26

      What is the real

2. 0:28 – 4:39

   The Real Problem of Consciousness

   1. CWChris Williamson0:28

      problem of consciousness?

   2. ASAnil Seth0:30

      Ha! I think it's, it's the s- approach to understanding consciousness that I'm taking, and I think a lot of my colleagues also are, whether they know it or not. The real problem is in contrast to the so-called hard problem. The hard problem of consciousness is this problem, which seems very hard, of trying to figure out how in the world something like conscious experience, yeah, felt experience, the redness of red, the sh- the sharpness of pain, how that is generated by or is identical to stuff happening in the world of stuff, in matter, biological stuff. We're made of stuff. It's complicated stuff, but it's still stuff. How does that give rise to conscious experience? That's the hard problem. Now, we can try and solve it head-on, but no one's managed to do that yet. The real problem of consciousness is the w- is, is just say that consciousness exists, some philosophers even would have us doubt that. Consciousness exists. We all know what it's like to have experiences of the world and self. And they're related in intimate ways to the brain and the body, so can we try to explain properties of consciousness, like what experiences feel like, why a visual experience is different from an emotion? Can we explain properties of consciousness in terms of the brain and the body? And I think if we do that, that's addressing the, the real problem, and whether we eventually completely solve the hard problem or not is still up for grabs. But let's see how far we get, and my suspicion and, and belief really is that by making progress on this real problem, then the hard problem will eventually fade away and just dissolve in a puff of philosophical smoke.

   3. CWChris Williamson2:18

      What would an explanation of the real problem of consciousness look like? I'm trying to work out what sort of form that could actually take.

   4. ASAnil Seth2:27

      It's ... could take many forms, and there m- there are many different forms. They all kind of move us away from what the neuroscience of consciousness started like, which was finding correlations between things happening in our experience and things happening in the brain. For example, a correlation could be your, part of your brain, maybe your frontal cortex, lights up when you consciously see something, but doesn't when you don't. And that's a correlation. It's useful to know, but it's not the whole story. It's not ... We, we ... It doesn't give us a sense of satisfaction, and we all know, intuitively and in other areas, that correlations are not the same thing as explanations or causations. Like, I think there's, there's things like the historical price of cheese in Wisconsin correlates with the divorce rate in France, a thing which is all, you know, fun fact-

   5. CWChris Williamson3:18

      (laughs)

   6. ASAnil Seth3:18

      ... but it doesn't mean anything.

   7. CWChris Williamson3:20

      Have you seen the correlation between, I think, it's the number of movies that Nick Cage was in in that particular year and the number of people who drown in their own swimming pool?

   8. ASAnil Seth3:31

      Well, may- maybe there is a causal link there. I mean, that seems potentially ... (laughs)

   9. CWChris Williamson3:35

      (laughs)

   10. NANarrator3:35

       Yeah.

   11. ASAnil Seth3:35

       You can't rule it out in that case.

   12. CWChris Williamson3:36

       People throwing themselves into their own swimming pool-

   13. ASAnil Seth3:37

       (laughs)

   14. CWChris Williamson3:38

       ... to escape the new Nick Cage movie.

   15. ASAnil Seth3:40

       It's ... It's, yeah, well, I mean, it seems unlikely, but you never know, but no, this is the point, that correlations, we can always find correlations, and the, the goal is to move from things that merely correlate to things that have explanatory and predictive value, so that we can say, "Okay. Ah, yeah, that makes sense, why that kind of p- pattern of brain activity goes along with that kind of conscious experience." And to make that link, the, to go from, "It just does," to, "Oh, it makes sense that it does," we need theories. We need theories that try to explain, um, why conscious experiences have the character that, that they do. And there are a number of theories on offer. The one I prefer and the one I work with mainly is the idea that the brain is a kind of prediction machine, and that different kinds of conscious experience are different kinds of brain-based prediction. And that gives a language for connecting these two different levels.

3. 4:39 – 13:10

   Why is the Self Rooted in Consciousness?

   1. CWChris Williamson4:39

      Why is being ourselves and having a sense of self related to a discussion of consciousness? H- h- how did those two things get related? We know what it's like to have this phenomenological experience of being yourself. We talk about it. The book is called Being You. Like, it's, it's ... But what's that got to do with consciousness? Why is the self-rooted in consciousness, and how do they relate?

   2. ASAnil Seth5:02

      I think it's central, and I think this is actually one of the side benefits, if you will, or maybe it's even the main benefit of the real problem of consciousness approach, because even if we don't solve the whole mystery, it changes the way we think about the problem. And in science and philosophy, often when you change the way you think about the problem, you change the questions, that's also progress. And so when it comes to the self, we might think that the problem of consciousness is really the problem of how we experience the world around us. You know, there's a world around us. It has objects in it and has people in it, and we experience them as moving around, having different visual appearances, and so on. But I think, for many of us, there is a sense of mystery about what the self is, and we might take it for granted and just think, "Well, there's this essence of me." You might wanna call it a soul or a spirit or something. There's this essence of me that is inside my skull, that is just there, and it's the thing that does the perceiving, and it's making the decisions about what my organism body does. And that's all there is to it. I mean, that's separate from the problem. I think it's the central part of the problem. Consciousness for each of us consists in experiences of the world.... but also experiences of the self, of being the individual that we are. And if I think back in, in talking to a lot of people, actually that's where the relevance of consciousness research often becomes most clear. So, I think most of us at one point or another in our lives have wondered, you know, "Who am I really? Why am I me and not someone else? Where was I before I was born? What will happen after I die? Am I the same person, you know, from one year to the next?" These are very personal questions, and so when we take the self to be not the thing that does the perceiving but an aspect of this flow of conscious experience that requires explanation itself, then I think we're making progress.

   3. CWChris Williamson7:05

      Yeah. I think when we're talking about consciousness, the, for the non-neuroscientists amongst us, it's the most front and center part of it, right? Everybody understands what it's like to have a felt sense of existing. They know what it's like. They, they, they go through these things. And they also-

   4. ASAnil Seth7:21

      They know what it's like... Sorry, yeah. Th- I mean, they know what it's like almost to the extent that you don't even think about it, because your, your self is kind of always there. You know, your conscious perceptions of the world change as you move around. And you might have different emotions, of course, and your experience of self does change, but it's, it's with you because it is you, so that might make it easy to overlook when you think about-

   5. CWChris Williamson7:44

      So, what is-

   6. ASAnil Seth7:44

      ... the problem.

   7. CWChris Williamson7:45

      W- w- what is the self? Is it a, a, a, a perception that we have of the, the thing that inhabits all of the different experiences we go through? Like, what does it mean to say that we are the same person now as we were 20 years ago?

   8. ASAnil Seth8:00

      That's a very complicated question, 'cause I think it makes sense in some ways but not in other ways. And the reason for that is that what it is to be a self is not one thing and the self is not a thing. It's a process. It's an unfolding process that encompasses different kinds of perceptual experience. One way to think of the nature of the self for an adult human being is to break it down into different levels. So, at the lowest level, as you said a minute ago, there's this basic almost unquestionable experience of just being a living organism, of, of merely existing. On top of that, we have emotions and moods. These are key parts of what it is to be a self. You know, an emotion is not a perception of something out there in the world. It feels within. It feels part of me, part of us. And then there's an experience of the body as an object. Again, very easy to take for granted, but when you think about it, we experience our bodies as separate from the rest of the world, and there are many conditions where this isn't the case, people with phantom limbs, people with other kinds of conditions where their brains create other experiences about what is or what is not the body. And then built on top of that, you have experiences of perceiving the world from a first-person perspective. That's part of the self. Experiences of agency and f- and the, and what we would call free will, which is not what most people think it is, but it's still part of the self in terms of the experience of free will. And only then do you get to the, the level of personal identity, the level of the self where you'd associate a name, a set of memories of the past and plans for the future, and a, a social network, a social influence on who we are. So, there are all these different dimensions of self-hood that are bound together for most of us most of the time in a seamless whole, but we know from lab experiments, from neurology, from psychiatry that they can and do come apart. So, the self is, is complex. It doesn't have to be the way it is. And when we ask, "Am I the same person I was 20 years ago or will be in 20 years' time?" in some ways, yes, some of these aspects of self might be quite similar, but others may well change. And we won't notice the change necessarily unless we, we s- have a sudden illness or something like that. Then we'll notice, 'cause it's very abrupt. But most of the time, the self changes slowly and smoothly and continuously, and so we are the same person, but what that person is, is itself changing.

   9. CWChris Williamson10:51

      Yeah. There's a sort of strange Ship of Theseus thing going on. I think every cell in your body has changed. Is it seven years? Something like that. I remember hearing, uh, it was a piece of breakup advice for girls, uh, that said, uh, "No matter how bad it hurts, don't worry, because in seven years' time there won't even be a cell left in your body that was around when you were in a relationship with your ex," which I always thought (laughs) was kind of a funny way of thinking about it. Uh, but even with that, right? So, that there is, there is a, a person that is you, and there are cells that made up you, but you are more than just the cells, because the cells can be replaced and yet your sense of self continues.

   10. ASAnil Seth11:27

       That's exactly right, and I think it would be... It's kind of strange to locate the self in a particular cell or collection of cells, but it's equally strange to not do that, right? Because then what is going on if it's not-

   11. CWChris Williamson11:40

       What the fuck is i- ... yeah. (laughs)

   12. ASAnil Seth11:42

       ... in the cells? And then where is it? It's in-

   13. CWChris Williamson11:43

       Yeah.

   14. ASAnil Seth11:43

       ... the organization, in, in the process. And this, this happens in other things as well, right? I mean, you have maybe a weather system, and all the different molecules of water probably change over time as well, and yet the storm system continues to have a coherent identity of itself. And the same thing, I think, is, is, is here. It, it's, it's another version of the, the Ship of Theseus argument. By the way, that's, that's the old kind of Greek story, isn't it, where you have a ship and you basically replace every part of the ship with a new piece of wood here, a new piece of wood there, a new rope here. And when you've replaced every single part of it, the question is, is it still the same ship? And-

   15. CWChris Williamson12:22

       Or Triggers Broom if you're British and grew up in the '90s.

   16. ASAnil Seth12:27

       Tr- and you're- you're- you're- no, you're shaming me now. I grew up in- well, maybe I'm too old.

   17. CWChris Williamson12:31

       Only Fools and Horses? You watched Only Fools and Horses, surely you-

   18. ASAnil Seth12:34

       I did watch Only Fools and Horses, yeah.

   19. CWChris Williamson12:36

       Come on.

   20. ASAnil Seth12:36

       Oh! Trigger- sorry. Yeah, yeah, yeah, I'm with you. I'm with you.

   21. CWChris Williamson12:39

       Trigger's broom.

   22. ASAnil Seth12:39

       Yeah.

   23. CWChris Williamson12:39

       The famous example for the Americans listening, there was this guy who was kind of an idiot that was a friend of all the other people on this comedy show, and he said that he was given an award by the local council for having used the same broom for eight years, and he couldn't believe it. And they said, "Hey, you made it with the same broom for eight years? That's amazing." He said, "Yeah, it's only had four new handles and three new heads." And everybody looked at him. So yeah, Trigger's broom is the British Ship of Theseus.

   24. ASAnil Seth13:03

       And that's why British comedy is so good, 'cause it's a philosophy lesson as well as comedy.

   25. CWChris Williamson13:07

       Fuck yeah. Um,

4. 13:10 – 19:39

   Thought Experiments to Understand Consciousness

   1. CWChris Williamson13:10

      but yeah, the- you know, the- this- this same sense of self, yeah. Is it- is it the cells? Is it the fact that you can just replace us? Is it the organization of the cells? But even if it is, does that mean that if I was able to recreate that organization elsewhere that that other me would be me? Well, it's no- is it- okay, so is it the fact that I, as me, inhabited this particular location, these particular coordinates, and had these particular experiences that I related to with all of my other experiences contiguously over time? Well, maybe, but what about if you're unconscious? What about if you go under general anesthetic? What about when you're asleep?

   2. ASAnil Seth13:43

      Right. So there- there- there are all kinds of weird thought experiments one can play about the self, and things that one can do in practice, like- like anesthesia. You know, on the first one, if you recreate all the parts somewhere else, then- then what happens? There's a very famous philosophical thought experiment, which I do talk about a bit in the book, called the teletransportation thought experiment, and this is the idea that, uh, you know, future or maybe even present Elon Musk in his next business venture develops this trans- teletransportation system where you go in, it scans you at whatever level of detail you think is relevant. You know, maybe the neurons, maybe every single molecule, maybe every s- every single atom or quark, and it recreates an identical- a materially identical version of you somewhere else, let's say on Mars. And the question is okay, so this happens, what happens to you subjectively? I mean, you're- you're in, let's say, I don't know, where it is, London, you get in the device and then you are rebuilt in Mars, but at the same time that you're rebuilt in Mars, you are destroyed in London. Like a whole bunch of lasers come and evaporate you, because we don't want a next continual explosion of people, it has to work that way. So you, going into this transportation system, should probably just experience yourself one instant you're in London, the next instant you're in Mars, or on Mars. And then one day, there's a mistake. The f- the system goes wrong and the automatic lasers which would have evaporated the London you don't work, and you're still there in London. And a technician comes in holding a gun and says, "I'm sorry, we've got to do it the old-style way, um, but the lasers didn't work." And then suddenly you have this, "But hold on a minute, I'm still here. So what is going on?" The- the temptation is to think you're either in London or on Mars. But really, you're probably in both places. And this- this highlights another assumption that we might make, which is another pop culture reference, like Highlander, that there can be only one. It... the idea of the self that is- is indivisible and unique, and I think this is probably wrong. If you do have exactly the same material thing, down to whatever level of organization, then you're gonna have the same conscious experiences. So in this case, initially there would be exactly two of you, one on Mars, one in London. But let's assume they didn't pull the trigger and you leave the- the system and you go wandering around. Of course, from that moment on, what it is to be each one of you changes, and you start to become different people, probably much like identical twins start off very much alike and then even though they're surprisingly similar, over their lifetime they still diverge because they've had different experiences, their brains change, their selves change.

   3. CWChris Williamson16:43

      Well, I don't think that... uh, even interestingly in that e- thought experiment, no one would think that the version of them that was scanned and the version of them that appeared in Mars, even if they managed to delete the old one and create the new one at the same time, I don't think anybody listening would expect for their s- felt sense to now be on Mars. I don't think that anybody would believe that they, their experience, would c- be one contiguous stream and then they would appear in Mars. I think it would be m- b- because then if that happened, and they didn't cut it, you would be split. What would happen? You- you- you'd be experiencing two lives at once like two eyeballs facing in opposite directions? I don't- I don't think that that's true either.

   4. ASAnil Seth17:26

      I don't know. That would be a question you'd have to... uh, there- there's a branch of philosophy called experimental philosophy where i- instead of making assumptions about what people would think in these cases, we- you know, you tell them and then you ask them. "So what- what do you think would happen?" I don't know. I mean, I- I think that if you describe it sort of s- properly, then I think it wouldn't be... i- i- it's a bit like the other example they use when you go to sleep or go under anesthesia. When you go under anesthesia, you lose consciousness entirely and you'll move from one room to another. You usually wake up in a recovery room which is different from where the anesthetic was administered, and most people expect to be the same person on the other side of that, right? They're not going from London to Mars, but they're going from one part of the hospital to another.

   5. CWChris Williamson18:11

      Yeah.

   6. ASAnil Seth18:12

      So what's the difference in that situation?

   7. CWChris Williamson18:14

      Yeah. Yeah, yeah, yeah. Yeah, why aren't you waking up as a different person? Why, when you wake up in the morning, do you expect to behave the same way as you did previously?

   8. ASAnil Seth18:23

      Yeah, because I think the brain has a very strong prior expectation...... that we are the same person. And part of that is justified, because not all of the molecules change overnight, and a lot of the, you know, the processes that shape our conscious experience, they maintain an integrity, maintain an identity, like the storm system maintains its identity over time as well. But we're not exactly the same people before or after sleep or before or after anesthesia, and I think that's fine, and I think recognizing and reconciling ourselves to the ever-changing self is, is actually both scientifically and philosophically accurate, but also quite helpful. And it, of course, echoes a lot of what people have been saying in, in things like Buddhist literature and meditative practice forever, that there's an impermanence to things, and there's an impermanence to the self and to identity, and we should not try and fight against that impermanence.

   9. CWChris Williamson19:25

      When you say that it might be comforting, it may have also spiraled somebody into this sort of recursive self, uh, skeptical thought loop, uh, that means they're now not gonna be able to leave bed for a little while, so I- I apologize if that's happened.

5. 19:39 – 22:40

   Are We Experiencing a Controlled Hallucination?

   1. CWChris Williamson19:39

      So moving on to s- how, how we and our consciousness relates with reality, you say that our experience of reality is that of a controlled hallucination. What do you mean by that?

   2. ASAnil Seth19:50

      No metaphor is perfect, but what I mean by this is that our experiences of the world, and of the self too, but let's stay with the world for now, are not direct reflections of some objective reality, like as if the world was just there and it poured itself directly into our minds through our eyes and our ears. It might seem like that, you know, we open our eyes in the morning or after anesthesia, and it just seems as though the world is there, and it has all these properties like color and shape and size and sound, and our brains don't seem to have much to do with it, but our brains have everything to do with it. And the idea, and it's not a new idea, is that instead of our perceptual conscious experience of the world being a process of reading the world out in this kind of outside-in direction, it's a process of active interpretation in which the brain is always trying to make its best guess about what's out there in the world on the basis of sensory information that comes in through the senses, but is ambiguous and noisy, and it doesn't have labels on, like it doesn't have a label saying, "I'm from a red thing," or, "I'm from a car." It's just electrical activity, and the brain has to make sense of it. And the theory, the idea is that it does so by basically having an internal model of the most likely causes of the sensory signals that it gets. And what we experience is not a readout of the sensory signal, but the brain's predictions about what causes those signals. And this is pr- a pretty big flip in how we relate to our experiences, because even though it seems they come from the outside in, they're actually, I think, coming from the inside out. And the sensory signals are there to keep our brain's predictions, our brain's best guesses tied to reality in ways that are useful for our behavior as a complex organism. That's where the metaphor of controlled hallucination comes from. Hallucination because experiences are internally generated, and when we think about hallucinations in everyday language, we typically think about something that's generated internally rather than something that's registering the outside world. But critically, the control is just as important. In normal everyday perception, our perceptual experiences don't just wander off into whatever they might be. They- they're very carefully regulated, controlled by the world and the body, and that's why perception, of course, works. That's why evolution has developed it that way, so that it's useful for us.

6. 22:40 – 32:29

   Looking at Perception Through an Evolutionary Lens

   1. ASAnil Seth22:40

   2. CWChris Williamson22:40

      Yeah, talk to me about how, uh, an evolutionary or a, sort of an ancestrally adaptive lens plays a role here. Why is it that we would have evolved this particular type of ability? Why is it that we would be making these predictions? What- w- w- what advantage does it give us, and- and how does that work?

   3. ASAnil Seth23:00

      I think it makes things a lot easier for complex organisms. It has to, maybe especially so for complex creatures like us. Um, if there were a one-to-one correspondence between some sort of sensory information, and something in the world, and what we should do about it, then we might not need any complex business of making predictions inside our brains. But things aren't like that. M- way back in philosophy, Immanuel Kant pointed out or made the argument that we can never perceive the world as it really is. We only perceive an interpretation, uh, s- a r- a r- I guess a transformation of it through a sensory veil. And sensory information that we get is not reliable. It's noisy. It's uncertain. It might come from different things. It changes according to the context, according to the environment, according to lighting conditions. And so to get a reliable indication of what's going on in the world, it's not enough simply just to funnel sensory information into the brain. It has to be interpreted. And mathematically, there's a, there's a way in which one might do this, like, optimally, completely perfectly, but this turns out to not really be possible for things to do in practice. So this whole process by which the brain makes a prediction of what's out there and then uses sensory information to update these predictions, that turns out to be a very, very good approximation for how any kind of system would solve this problem of figuring out what's there under conditions of uncertainty. So it's-

   4. CWChris Williamson24:36

      Why, why not just...... absorb what's there. I don't know if I'm being thick here, but wh- why, why not just observe it the way that it is? Why do this other thing?

   5. ASAnil Seth24:46

      Well, take color for example. Take our experiences of color. Now when we experience color, this is a useful thing for, for brains to provide our experience with, right? Because colors allow us to keep track of surfaces when lighting conditions change. They highlight things we might miss like the color of a ripe fruit in a tree. Very, very useful. But where are colors in the world? Colors don't exist out there in objective reality anyway. There's just electromagnetic radiation that goes from radio waves to gamma waves, and our eyes are only sensitive to three wavelengths of that radiation. And out of those three wavelengths, we experience millions of colors. So when we experience color, we're experiencing simultaneously less than what's there 'cause it's just three wavelengths out of a long, vast spectrum, and more than 'cause we experience, uh, millions of colors, not just three. So in this case, it wouldn't really be very useful to, for us to experience what's really there because what would that mean? I- it would mean that we experienced a continuous kind of set of wavelengths from, you know, kilometer long to, you know, whatever x-ray however long those are. It's not even clear what that would mean to experience that. And yet we don't even experience a small subset of that. We create, the brain creates something out of the sensory environment that is very useful for us. But you can put it even more simply, like, what's really out there? Is it objects or is it atoms or is it quantum foam or something? Nobody really knows what's out there anyway, so to put as a benchmark experiencing things as they really are is, I think, just to misunderstand what kind of business a brain is in. Just, it's in the business of helping us stay alive.

   6. CWChris Williamson26:42

      This doesn't feel... Is it Donald Hoffman? Is that the guy that's got the kind of ideas that the world is very different out there? This doesn't feel a million miles away from what he talks about.

   7. ASAnil Seth26:53

      It is similar in some ways. So yeah, Don Hoffman has his idea of an interface theory of perception, which is that what we experience is some kind of user interface which in- which intervenes between how the world really is and something that's useful for us to, to survive by. We agree in the sense that the contents of experience are indirectly related to what's going on out there in the world, but there are two places where we disagree. One is this metaphor of a user interface I think is problematic because it suggests that there's some kind of mini-me inside my head, you know, looking at this interface much as I might look at a computer screen and clicking on this icon or that icon. Whereas back to the self, I think the self is part of the interface. There is no me that's separate from the flow of experience, and I think things that, that bring back, that smuggle back in this inner h- homunculus, uh, uh, is not the way to go. And then we also disagree, and this is something that I've talked to him, uh, a few times about. He then also makes a whole bunch of claims about the real nature of what's out there in terms of little conscious agents everywhere, and, and I've not yet been persuaded by his ideas on that. I might be in the future, but I haven't been yet. And you don't have to go that far. You can still just try to understand the nature of perception as solving this indirectness between how things are in the world and what's the best way for the brain to make sense of things in order to survive.

   8. CWChris Williamson28:32

      I remember reading, uh, a- an explanation for an adaptive, uh, justification for consciousness, and i- included in that was the fact that as complex social beings who have to manage our own, uh, uh, interpretation, our own status, you have to be able to model that of other people and how that other person is interacting with that other person and so on and so on and so on and so on. How important do you think the complex social networks of ancestral humans has been to, uh, encouraging this predictive, uh, sense that consciousness sort of has?

   9. ASAnil Seth29:10

      I think it's important, but I think its importance can be, and sometimes has been, taken too far. So we think about what it means to be an adult human self. We often put a great deal of emphasis on the, the level of personal identity, you know, the me being Anil Seth, you being Chris Williamson. We ha- we have these i- we have these identities being particular people, and at the level of personal identity, the social aspect is very important. We have to differentiate ourselves from others, and we have to, at the same time, predict the behavior of, of others too. So modeling the minds of others is, is absolutely key to our actual everyday behavior, and it may even be key to some aspects of what it means to be yourself. So it could be, as some people have argued, one of, one, uh, one of my mentors, Chris Frith, has made this case that the reason we know about our own mental states, like, you know, when I have a, an experience, I don't just have it, I know that I have it. I can talk about it. The reason I have this insight into my own mental states is because my brain first evolved the ability to predict others' mental states, and it's that kind of theory of mind that then wrapped itself back into within the organism and gave each individual a more elaborated sense of self. I think that might be the case, but I think you can go too far a- and say, as some do as well, that that's necessary for any kind of consciousness, that that's why we have conscious experiences.... and that's why we have selves. For me, I actually go right the other way, and I say the origin of the predictive brain, the reason we have predictive brains, is fundamentally because of the brain's need to control and regulate the body. And if you think about what brains are generally for, not only in humans but in other animals as well, the primary duty of any brain is to keep itself and the body alive, and the best way to regulate the body is to be able to predict what's going to happen to it. Predictions that any control engineer will tell you, when you can have a predictive model of a system, you can much better control it because you can stop it going wrong before it even starts to go wrong. Like if you had a, if you had, um, a central heating system or an air conditioning system that predicted the change in the outside weather, you could keep the temperature of your house much more stable rather than just reacting to changes as they happen. So for me, that is the fundamental reason why brains evolved this ability to make predictions about sensory signals, and everything else gets built on that. Our ability then to predict what the body is like, to, to make perceptual predictions about what's out there in the world, think it's plausible all this machinery rests on this fundamental imperative to stay alive. Eventually, social predictions become important as well, but if you want to figure out what's fundamental, I don't think we look there.

   10. CWChris Williamson32:23

       That's very interesting. It's very interesting to think that it, it's not necessarily what, what's important.

7. 32:29 – 41:17

   Studying How to Alter the Predictive Brain

   1. CWChris Williamson32:29

      What... You've done a ton of experiments that kind of show how the predictive, as opposed to the perceptual, side of the brain can cause people to, um, erroneously predict, I guess. Could you explain some of your favorite, uh, examples of that?

   2. ASAnil Seth32:48

      (laughs) So there's, there's ano- this is one of the fun things about this kind of job is that the experiments can be quite illuminating but also entertaining, and this idea that, uh, what we perceive is a kind of controlled hallucination begs the question, if we change things, can we change people's experiences in ways that would be aligned with this idea? We've done this in a few different ways. So, in one experiment, we wanted to simulate what it would be like when people's brains had overly strong perceptual predictions. So their controlled hallucinations become a little less controlled, you know, and more little hallucination. And... Sorry, let me say that again because more little hu- so... (laughs) . We wanted to try and understand what would happen if people's brains had overly strong perceptual predictions, so a little more hallucination, a little less control in the controlled hallucination, and we did this by using a neural network, the sort of thing that's pretty old hat now given the, the developments in AI, but a, a powerful neural network that's able to classify what objects appear in different images, and we ran it backwards using an algorithm that was adapted from what Google called Deep Dream. We ran it backwards. So basically, it just takes a, a category of object, like dog, and it projects that back through the image to simulate a kind of hallucination of dog. And we did this with a 360-degree panoramic video of Sussex University, and then we gave people headsets, virtual reality headsets, to wear and replayed the video so they could look around in all directions and see what was going on. And the result is kind of striking. It's a really immersive experience, and it's a, it's a model not of what people do or how they behave, but it's a model of a different kind of conscious experience.

   3. CWChris Williamson34:48

      Yeah.

   4. ASAnil Seth34:48

      And the initial experiment was just a proof of concept. It wasn't really like any specific experience. People said it was a bit like psychedelics, but I don't think it was. And now what we're doing is making it much more specific. So we're taking this proof of principle, and we're developing it so that we can s- model different kinds of visual hallucination. So people that have Parkinson's disease have hallucinations of a specific kind. People who have visual loss have hallucinations of another specific kind. And we can now begin to understand these differences in terms of different ways the predictive brain can go wrong. And by doing this, we can understand much more about how the p- predictive brain works in a normal case. Again, there's a lesson from engineering here that if you want to understand how a system works, you kind of look at how it breaks in various ways, and that gives you a clue about what's going on in, in a normal case, which you might otherwise miss things that you would take for granted. So that's kind of a cool... Uh, I'm, I'm enjoying this experiment because it involves just modeling weird kinds of experiences and then going out and testing whether they accurately reflect what people in the world with these different kinds of hallucinations really experience.

   5. CWChris Williamson36:04

      We've also seen other sorts of experiments where people have had their, is it corpus callosum, severed, and then you can do all manner of strange things with d- different hands, right hand being related to the left hemisphere and left hand being related to the right hemisphere. You can do things where you show images to different sides and people have to put their hand into bags and select certain things out. How much is that related to this discussion of consciousness, and how much is that just, uh, I guess an artifact of the fact that we've got this criss-cross brain-body connection?

   6. ASAnil Seth36:37

      I think it's very related, and it's, it's still a- a- absolutely fascinating area. There was a lot o- most of this work was done quite a while ago, because back in the '50s, '60s, '70s, when people had really severe epilepsy...... there weren't that many options to treat it, and one of the options, quite a radical option, was this kind of surgery. It's called a callosotomy, and it is basically cutting this big bundle of connections that connect the two brain hemispheres. It sounds incredibly brutal, but the surprising thing is that if you do it, it seems to have surprisingly little effect and people, they're pretty much the same. And you can only find differences in these quite weird situations where you show different information to the different hemispheres, and then all of a sudden it seems like something strange is going on. And it's very relevant to consciousness because it immediately raises the prospect that are there now two conscious selves sharing a single brain? That's kind of weird. And it's still a little bit unresolved. I mean, these days one of the side effects of better medical treatments for epilepsy is that these operations aren't done so much, and if they are done, they're not done where you separate all of the, um, hemispheres. You usually leave some- some bits in tact. Now, this is great medically but it's- it's kind of deprived us of this wonderful, strange, um, you know, almost living thought experiment of a split brain. And the story as it is now... I have a colleague, a former postdoc of mine in Amsterdam, Yai Pinto, who's sort of picked up the chase and tried to- tried to do a lot of these experiments that have been done in the '60s and '70s again. So like a classic experiment, as you say, would be, um, you'd give- you'd show a picture which one brain hemisphere would see and, um, it would- you'd ask it to draw what it saw and then you'd ask the person what- why they drew what they drew but having shown that hemisphere another word. And so what's... uh, it's a- it's a bit hard to explain, but basically one hemisphere is usually where the neural circuitry for language resides, usually the left hemisphere in- in most- most adult humans. And so the left hemisphere which sees the right visual field can describe what it sees, but the left visual field which goes to the right hemisphere doesn't usually involve language. It can, but it can sort of do other things. It can draw, you know, with- with the left hand now 'cause everything is crossed in the brain so where left goes to right, right goes to left. And when you introduce a conflict then the- the left hemisphere which can speak will often just make something up to explain what the right is doing. It'll confabulate, um, but it will be completely weird and- and wrong and you have this uncanny sense that the left hemisphere is- is just unaware of what the other half of its- of the brain is doing. Now, these days it seems to be a little more finessed than that. These massive separations, they may be not quite so dramatic. They might resolve over time. But there are still differences. There's definitely differences in- in how people with split brain, um, operations, how they can integrate information across the whole visual field, and there is still this fundamental question about the unity of consciousness. Can it be divided and what does that- what does that even mean? I find that it's probably not resolvable but it's- it- it- it just- it provokes our assumptions about what we are. I mean, again, we have this- this idea, just like the teletrans- transportation experiment, that we are one thing and unique and indivisible, but there are all sorts of ways that the self can come apart and this is just one of them.

   7. CWChris Williamson40:38

      Well, people have, uh, areas of the brain that are removed or damaged for a variety of reasons and, you know, consciousness persists. Perhaps their personality changes. So, consciousness is, it suggests, at least in part distributed in some regard. It can't- it can't be necessary for every single bit of the brain to be operating the way it is for consciousness to persist. Maybe- maybe that per- person is somehow less conscious if they were to lose 5% of their brain because a- a railway sleeper or whatever, railway screw goes through the top of their head or whatever that famous story is.

8. 41:17 – 45:38

   Where Does Consciousness Arise?

   1. CWChris Williamson41:17

      But it- does it make sense to ask the question where does consciousness arise? Is- is that even a- a- a question that makes sense?

   2. ASAnil Seth41:26

      It makes some sense, (laughs) like- like all these questions. It doesn't make sense if you're looking for one place, you know, the seat of the soul. I don't think it makes sense that way. But one of the most, uh, I think most informative aspects of the neuroscience of consciousness in the last 20 years has been to try and identify those parts of the brain that are more involved in consciousness compared to those that aren't. And it will change. It changes depending on how you look. But there are some things which are relatively clear. One of the things I- I find always a bit surprising is that three-quarters of your brain, if you count it by number of neurons, number of brain cells, three-quarters of your brain does not seem to be much involved in consciousness at all. This is the- the cerebellum. So our brains are organized into these two hemispheres, but we also have this kind of mini brain at the back, cauliflower-shaped thing, called the cerebellum. It is very important in controlling how we move and maybe even in orchestrating how we think, you know, the ability to do things in sequence and so on, but it doesn't really seem particularly implicated in consciousness. There are some people born without a cerebellum. That seems absolutely fine. All the brain activity that- that we... When we contrast things like what happens when somebody loses consciousness or when they're conscious of something and versus not...... it never really involves the cerebellum, so the mechanisms that are most relevant for consciousness are elsewhere, and they seem to be in the cortex, maybe underneath the cortex, so in the more, in- in the more frontal parts of the brain compared to the cerebellum. And here, it's still just a big open question. There are some experiments and some theories, and here I- I've must, I must admit, it feels a little, a little depressing that after this long and, you know, the advanced technology that we've got and so on, one of the main debates in the field is still about whether consciousness is more in the front of the brain or more in the back of the brain. I mean, great, but it's- it's a bit, it's a bit blunt, isn't it? I mean, that's- that's quite a big contrast, and it's still unresolved. And part of the reason it's unresolved is there's one extremely tricky problem with studying consciousness, which is that we only know what people are conscious of if they tell us in some way, whether through words or through pressing a button or through some other way of reporting what they're conscious of. And the challenge here when we look at what's happening in the brain is how do we separate what's happening in the brain that actually underlies what we're conscious of at any moment and what is just necessary for us to talk about it, to report it? And it could be that the experiments that say the front of the brain is critical, well, they s- show that, but actually what they're showing is that the front-of-the-brain mechanisms are important for our ability to say what we're conscious of, but not for the conscious experience itself. So, the last few years in this field, a lot of it's been about trying to get around that, whether it's through theory or through clever experimental design. It's a real challenge, but it's an exciting challenge because, you know, I think it's overcome-able, just not simple.

   3. CWChris Williamson44:59

      Yeah, I guess i- it's almost like that section of the brain is a little bit more of the philosophical zombie. It is the one that is able to explain it but less so the one that is actually the experiencer of it.

   4. ASAnil Seth45:10

      That- that- that's a very nice way to put it. That may be the case, but then there are other people who say, "No, actually those are the same things." It's kind of the ability to explain what's going on in another part of the brain-

   5. CWChris Williamson45:20

      Mm-hmm.

   6. ASAnil Seth45:21

      ... that is the experience, so there are various theories like there's a theory called higher-order thought theory which basically says that, that consciousness is in the act of one part of the brain explaining or looking at another part of the brain-

   7. CWChris Williamson45:33

      Mm-hmm.

   8. ASAnil Seth45:34

      ... but then other theories would be the other way around.

   9. CWChris Williamson45:36

      So, given that it- it

9. 45:38 – 49:36

   Testing the Consciousness of Lower Animals

   1. CWChris Williamson45:38

      seems like there's varying parts of the brain that are, uh, involved in, uh, varying degrees to our experience of consciousness, and there are chunks of it that are the latest in terms of our evolution to develop that seem to be a little bit more a- a- advanced, is it right to say that lower-order animals in that case aren't conscious? Have you got any idea whether or not other animals are conscious? Do they meet a threshold or a test by which you would be happy to say that they are?

   2. ASAnil Seth46:04

      It's so interesting you mention test, and one of the active projects I'm involved in right now is, what do we even mean by a test for consciousness and h- how, what would we want from one and how might we develop it? Because it's not just in non-human animals. It's also in brain-damaged people, it's in newborn infants, and it's, of course, in new technologies like, um, AI and also neural organoids, which are collections of brain cells grown in the lab. So, there's lots of- lots of areas where we might want to test for consciousness because, well, firstly, for- for moral and ethical reasons. As soon as something is conscious, it has some sort of moral status, some ethical status. For non-human animals, I personally think, it's very hard to know for sure, but this is part of the problem, we can't ask them, but if we look at the preponderance of evidence in terms of what brain mechanisms are shared with other species that we know or have good reason to believe are important in human consciousness, then I think it's fairly clear that all mammals have some kind of conscious experience, even if they can't tell us about their conscious experiences. They share the same parts of cortex and the bits underneath the cortex, the thalamus, that- that just are very deeply implicated in human consciousness. When you get beyond mammals, it becomes harder because we don't have a consensus theory of consciousness that we can generalize to- to other things very easily. It's going to be a kind of what's our best guess, you know, what- what's the best thing we can say with the limited evidence that- that we have? And here, it depends on what kind of theory about the most important aspects of consciousness are. If you think, as we said earlier, like if you think having a sense of theory of mind and being able to predict what other people, other animals are going to do is important, maybe it's quite restricted. If you think consciousness is co-extensive with something like intelligence or social intelligence, then maybe it's not present in that many other species.

   3. CWChris Williamson48:20

      My dog doesn't know whether I'm going to go left or right or whether it's whatever time or this other time.

   4. ASAnil Seth48:25

      But it might even, you might, some people might even make a stronger claim that because your- your dog can't do that, it's not conscious at all.

   5. CWChris Williamson48:32

      Yeah. Yeah, precisely. Precisely.

   6. ASAnil Seth48:34

      It's like a dog zombie.

   7. CWChris Williamson48:34

      Yeah, yeah, yeah.

   8. ASAnil Seth48:34

      I think, I think this is... I- I find this unappealing, and not just unappealing because I like to think dogs are conscious, but I find it theoretically unappealing because I think that the roots of conscious experience are in the- the need for brains to regulate the body, to keep the body going in environments where there's a lot of information in their sensory world that pertains to how the brain regulates the body. So, if you think consciousness is more rooted in this- this fundamental process of-... physiological regulation, then you're gonna be more liberal about how many other creatures have it, and you- you might start to think, okay, you know, it's not just mammals, it's- it's- it's maybe birds, it's maybe cephalopods like octopuses and squid, it's- it's maybe even fish.

   9. CWChris Williamson49:26

      I'm down for- I'm down for octopi. I'm down for octopi being conscious, man. I've read enough sci-fi stories about-

   10. ASAnil Seth49:32

       (laughs)

   11. CWChris Williamson49:32

       ... super-intelligent octopi. Um,

10. 49:36 – 59:10

    The Most Common Definitions of Consciousness

    1. CWChris Williamson49:36

       what is the most commonly used definition of consciousness that is the barometer that most researchers in this field are using to work out whether a threshold has been crossed or not?

    2. ASAnil Seth49:52

       Huh. So the definition doesn't really provide a threshold, which is part of the problem. I mean, the definition that most people use, people use different definitions, but a fairly good one comes from the philosopher Thomas Nagel, who says, "For a conscious creature, there is something it is like to be that creature." It feels like something to be me, it feels like something to be, um, a dog, but it doesn't feel like anything to be a table or a chair. It's what makes a conscious creature more than just an object. That's the intuitive definition. That, of course, is just a description. It doesn't give you something that you can then go and- and measure. And the- the consensus about what to do in that, what to actually go out and measure, well, there is no consensus. It's- it's a very febrile area of discussion, and- and it depends what kind of consciousness people are looking for. So a cl- a- a well-used test in the sense of that's been used a bunch of times is the mirror self-recognition test. So the mirror self-recognition test asks whether an animal knows in some sense that its mirror image is itself rather than another animal. We humans, we do this naturally. We look in the mirror and, for better or worse, we know that it's us. But this ability in humans doesn't appear at birth. It takes several months. It takes probably over a year to develop in- in human infants. What does this mean? It means that it takes a while for that aspect of self-consciousness to develop. It does not mean that consciousness was entirely absent before then. It just means the aspects of perceiving one's self as a distinct entity, that might take quite a while, and may be restricted to a few species rather than loads of species. At the other end, you might say something about responsiveness to pain. And here I have a lot more sympathy. So you can look at what animals will do when they are subjected to some- something damaging or- or painful, and not just do they run away, but do they do the kind of constellation of behaviors that we associate with our conscious response to pain? Do we tend the wound? Do we go to somewhere where there's anesthetic available? Um, do we change our whole organization of our behavior so as to aid recovery? I think this is- this is the most sensible place to look. It might- it might be a bit, you know, you have to pick where on the scale you want to- you wanna make, do you wanna be overly conservative or overly liberal? 'Cause you're not gonna get it bang on. So in- in my, you know, in my feeling, pain is important. If- if a species, if a creature has the ability to suffer, then it's really deserving of a place in this sort of charmed circle of ethical and moral consideration.

    3. CWChris Williamson53:04

       Yeah, I was thinking about a snake and, uh, something tells me that a snake can't reflect, it can't, uh, recognize itself in a mirror. But if you s- stick a stapler into the side of it, it's- it's probably gonna know.

    4. ASAnil Seth53:17

       It's gonna know for sure, yeah, yeah. (laughs) I don't know, I mean, I have actually no idea whether anyone's done the mirror self-recognition test on a- on a snake. I mean, this is also part of the problem. These experiments are quite hard to do, and we've only studied a handful of species with any sophistication at all.

    5. CWChris Williamson53:33

       Not that hard to do. I mean, get- get a snake, get a mirror, stick it, stick it on the floor. You know what I mean? Like, it's not that hard.

    6. ASAnil Seth53:39

       Well, you know, you say not hard to do, but you get, you know, you have to do it several times. And also there's many reasons why animals fail this test, like, um, many animals don't like to make eye contact, and some don't like mirrors, so they're just gonna fail this test for reasons- for other reasons. So even then, you don't know how to interpret the results.

    7. CWChris Williamson54:02

       Well, I was- I was thinking, as you were explaining the mirror self-recognition test, I was thinking about, uh, bats or voles that have got particularly poor eyesight, basically no eyesight, or what about an animal who's had both of its eyes damaged?

    8. ASAnil Seth54:16

       Yeah.

    9. CWChris Williamson54:17

       If it's never able to detect itself, does that mean that it's no longer conscious? Again, like...

    10. ASAnil Seth54:21

        Yeah, probably not, right? I mean, that- that was Thomas Nagel's point in his- his paper where we, where the definition of consciousness came from that we- we've been talking about. His paper was, what is it like to be a bat? And, uh, it's a very interesting thought experiment because bats, of course, have echolocation. We don't have anything like echolocation, um, so it will be impossible for us to experience being a bat unless you actually are a bat. With the potential exception of, not Batman, but there's this, there's a few people who have developed so-called human echolocation, so people who've gone blind or who were born blind and have developed the ability to make clicking sounds and perceive the layout of their environment through processing the echoes.... to these clicking sounds.

    11. CWChris Williamson55:13

        Do-

    12. ASAnil Seth55:13

        I find this really, really interesting. It's, it's ... You know, we- our brains didn't evolve to do this, so it's not going to be as good as a bat's, not as good as a bat, but it's, it's the closest that we might be able to get.

    13. CWChris Williamson55:26

        The weirdest first date that I ever went on was at, I think it's called Café Noir in London. Have you heard of this?

    14. ASAnil Seth55:35

        Is this where they serve food in total darkness?

    15. CWChris Williamson55:38

        Correct.

    16. ASAnil Seth55:38

        Yes.

    17. CWChris Williamson55:38

        And it's blind, it's only blind servers. Now, I think that rather than using echolocation, the servers have just memorized the room's layout incredibly well, but, you know, my bedroom ... I, I tried to go to the bathroom last night while it- without turning the light on so it wouldn't ruin my sleep and I crashed into something. I've been in that room, you know, hundreds of times, so there is some part of their spatial awareness, their proprioception which has been tuned up for them to be able to carry plates through a room with tons of people in, all talking, and not drop it on the wrong person, remember where they're going, find the person of where they're going, et cetera, et cetera. Um, but yet that was, that was the first date. I don't know what it says that this girl decided to take me into a room where she literally couldn't see me. Um, I'm not really too sure what that says about our first date, but it was really fun actually.

    18. ASAnil Seth56:32

        (laughs)

    19. CWChris Williamson56:32

        And I remember thinking at the time, "There's something going on here. There is something that has happened to allow these people to compensate for..."

    20. ASAnil Seth56:40

        And is it ... Yeah, it's, it's fascinating. And, and the thing is, uh, I know your example of y- y- you kind of stumble around in the darkness trying to find a bathroom, but, you know, if you, if you adapted to it, if you gave yourself time, then you can do surprisingly well at picking up just these very subtle cues out there. And if you think about these waiters in Café Noir, imagine like how much better you get at moving around in the dark after just trying to do it for an hour and then just imagine that they've done it for a lifetime. Maybe it's not so surprising that they're, that they're really good. But about the, the mirror thing, I mean, it is true that we tend to overemphasize or we tend to strongly emphasize visual stuff as humans. We, we feel, we're very visual creatures. And again, that bias may lead us astray when thinking about other animals. The mirror self-recognition test seems to be a visual test, but there are some researchers looking, for instance, you know, it didn't even go to bats, you go to dogs. Dogs, uh, they have vision, of course, but for dogs, smell, olfaction, is so much more important. So there are people trying to develop an olfactory mirror test for, for a dog. And I'm not-

    21. CWChris Williamson57:55

        (laughs)

    22. ASAnil Seth57:55

        Don't ask me quite how it works. I, I have no idea exactly what they do, but I like the, I like the point that, that if you ... You have to, you have to try and understand the ecological niche or as the ... There's a German, um, philosopher, psychologist called Jakob von Uexkull. He came up with this concept of the umwelt, the kind of lived world of another animal. So if you were a bat, you know, your world is suffused by, by echolocatory signals. So you kind of would have a sense of where things are, um, that wouldn't be visual, but it would be like having radar or something like that. And then bees have another umwelt entirely where, where the light reflected from, um, in the UV or infrared becomes very prominent. And I think this is a ... There's, there's a wonderful book by, by Ed Yong called An Immense World which, which really highlights that it seems as though we're sharing the same world, but if you, if you have, you know, a human, a mouse, a bat, an elephant all in the same space and assume they're all conscious and ask, "Well, if they are conscious, what would their experiences be like?" Their experiences are so different.

    23. CWChris Williamson59:08

        Well, I suppose what's

11. 59:10 – 1:05:32

    The Challenge of Testing the Internal Processes of Animals

    1. CWChris Williamson59:10

       interesting about that example of having a number of different animals within the same environment and then let's say that it's a, a maze or that they, they just need to go about and do their normal thing. They need to maybe find some food and some water and do the rest of it. From the outside, you can observe behavior which looks like it could be coming from the same place, right? Because the net outcome of their behavior is the same. It may do it in different ways, but the net outcome is that they eventually find some food and they find some water and they go in shade when it's hot and they go into sunlight when it's cold and blah, blah, blah. But internally, how each of those animals arrives at the thing that it's doing to track down the food, the human may heavily rely on its visual field, the dog may heavily rely on its olfactory senses, the mouse may use ... Uh, if it was a bee, the bee would have, uh, ultraviolets. Um, it can see ultraviolet light. So okay, you're, you're able to produce behavior which is not only adaptive and useful, but from the outside might not look all that different, and yet the route at which each animal got to it is completely different.

    2. ASAnil Seth1:00:19

       Well, let's linger on that for a second. I think there's, there's something worth unpacking here because in this example of, I don't know, a mosquito, an elephant, a human, uh ... It sounds like a bad joke, doesn't it, go into a bar.

    3. CWChris Williamson1:00:30

       (laughs)

    4. ASAnil Seth1:00:30

       And, um, they're all in the same bar. And I think in this case, the behaviors are quite different. Like in a mosquito will detect levels of carbon dioxide and, you know, be able to use that to find skin. I think that's what they're sensitive to, I can't remember now. But they'll be sensitive to very different kinds of things and, and, and will do things that seem a bit uncanny, like, you know, move around in the, in the dark. You know, mice are so sensitive in their hearing and sense of vibration that they'd be able to ... Runaway owls can hear things at such a vast distance that it, it ... The behaviors would be different. And so it's maybe easier to recognize that the perceptual world, the umwelt of these creatures would also be different to us. I think where we might make mistakes is actually within a species.So, if you have a bunch of people in this room, in a room and they're all, you know, interacting with each other, then you're right, they may all do the same sort of thing. They may all look for food, they may all go fr- to the shade when it's hot and so on. And just in general, in our everyday lives, we tend to expect people to behave in a way that we might behave, more or less. And so it's very easy then to assume that other people experience the world the same way we do, because their behaviors might be relatively consistent compared to, you know, the difference between me and a mosquito. But I think this is a mistaken assumption. It seems to us we see the world as it is, and we use the same words often to describe things. Like I see a red car, you see a red car, we both say, "It's a red car." And so we assume then that we're having the same internal experience of this shared objective reality, and I don't think that's true. In fact, I know it's not true. In fact, this is not a new thing to say. There's plenty of evidence out there of people who experience the world in very different ways. You know, they have hallucinations and, and so on, have synesthesia when people see colors when they hear sounds and mixing of the senses. And of course, there's the whole, um, area of neurodiversity which really highlights that there are, there are substantial differences in how different people encounter a shared world. But I think we still underestimate what's going on because at the moment, unless we are hallucinating or unless we associate ourselves with a neurodivergent condition like autism or something like that, it's easy to assume that we're neurotypical and we experience the world just as it is, and I don't think there is such a thing. I think that we all differ. And understanding that, unpacking that, I think is a, is a great challenge because we, we know the importance of taking into account and actually, um, you know, really relish- relishing, I'm trying to think of the right, (laughs) the right word here. Not just take into account, but, um, recognizing the value of diversity that we can see on the outside. You know, diversity in cultural background and, and, and body shape, size and so on, but we also have this inner diversity. And it's, if we don't recognize that it's there because we use the same words and it seems as though we see things as they are, I think we're, we're losing an opportunity to, to, um, benefit from a diversity of ways of perceiving, of ways of seeing things. And this is a, this is a, sorry, it's a very long-winded way of mentioning that we have a project at the moment called The Perception Census, which is trying to do exactly this. It's a big citizen science project where we ask people to join in and do a bunch of pretty simple and fun little interactive visual illusions and so on, to try and help us get, uh, a picture of perceptual diversity to map out this hidden landscape of, of inner variation. And it's online. It's, all you need is a computer and you can-

    5. CWChris Williamson1:04:52

       Where can people go if they want to try this out?

    6. ASAnil Seth1:04:54

       If they just, um, look for Perception Census, just type that into Google or go through my website, just look for anilseth.com. It'll take you straight there. And you can do a little bit. You can set it aside, come back, um, and we'll keep track of your progress, and you'll learn a lot about perception and your own particular way of perceiving the world. We've already had about 26,000 people try it now and from a hundred countries. So, we want to make this a real landmark study both to map out this perceptual diversity, but also to raise awareness that it's actually there. And I think that will be of quite some sig- significant social value.

12. 1:05:32 – 1:11:04

    Anil’s Experience with LSD

    1. ASAnil Seth1:05:32

    2. CWChris Williamson1:05:32

       Talking about perception. What happened when you took LSD?

    3. ASAnil Seth1:05:37

       Quite a lot. I mean, I didn't take LSD until I was in my 40s. I didn't have the opportunity or probably the desire when I was a teenager in South Oxfordshire. And at some point, it seemed like the right thing to do. I guess I really wanted to know what it was like from the first person. You know, thinking about consciousness a lot, for me, it doesn't do this for every researcher in this area, but for me, it made me very curious about what kinds of conscious experiences are available because part of the whole motivation for me is understanding what we take for granted in our own experience because it's always been there or it's always been some particular way and not another way. So, ways to get out of the perceptual habits that we're in, I think can be very illuminating and there are many ways to do this. There's, there's meditation, there's jumping out of a plane, there's all sorts of things, right? But psychedelics is one obvious way and-

    4. CWChris Williamson1:06:41

       Pretty reliable.

    5. ASAnil Seth1:06:43

       It's very reliable. And it's, and it's reliably substantial. Y- you just know so... Well, this is what I was expecting and this is what I've been told and in fact this is true, right? You, you put some, you put a little tab on your tongue and under your tongue and then stuff will happen, and it will happen for a while. And I think I was... I was both reassured and surprised, and the way to explain that is nothing happened that I didn't expect to happen. But the fact that it was happening to me was still surprising.And what it involved was, uh, large changes in my perceptual environment. You know, things became much more fluid, things became much more changeable. There seemed to be this influence that I could have over what I was perceiving. By almost willing clouds to change into things, they did. Things started to bleed together and things became imbued with this sort of sense of quite magic and there, there would, there would be this quality to the whole environment that, that changed, and of course, the sense of self-changed as well, and, um, it's very... it's notoriously hard to describe these kinds of experiences without sounding entirely naff. I think Michael Pollan has done a good job in his book, How To Change Your Mind.

    6. CWChris Williamson1:08:10

       Well, if, uh, if Aldous Huxley... you know, if we have to call on one of the greatest wordsmiths of all time to try and tell us what he thinks in Doors of Perception, then yeah.

    7. ASAnil Seth1:08:20

       Yeah. It's... it, it's hard and I, I don't want to mangle these things, I'd rather just appeal to these kinds of authorities, but, but it was... it was... you know, I, I'd been prepared to be disappointed, I think, about, okay, it's... it's... well, that wasn't quite as transformational as I'd... as I'd been hoping for, but it was. I was not... I was not disappointed, and it is... it is remarkable. I think the other thing that, that... it's interesting that, for me, it just reinforced the, the idea that I went in with, that our conscious experiences are biological phenomena in the same way that anesthesia did. You know, anesthesia, for me, shows that you can... if you change the brain in a very specific way, you change consciousness in a very reliable, predictable, specific way as well. With anesthesia, it goes away and then comes back. With psychedelics, again, you're... you're intervening in the system in a very precise and very specific way and your conscious experience changes in a very... you know, the details may vary, but the overall trajectory of what's happening is very predictable.

    8. CWChris Williamson1:09:32

       Yeah. So, the... the implication here is that if consciousness wasn't something which is, as you had predicted, it shouldn't be able to be impeded or imposed on by these sorts of substances. You shouldn't reliably be able to change it because it should be something which is outside of the... the, the, the changeable.

    9. ASAnil Seth1:09:54

       It's interesting because some people would take entirely the opposite conclusion and, you know, the fact that a psychedelic experience may give you a sense that you... you're outside of your body or that yourself is part of the universe, you may take these experiences at face value and reach the conclusion that their normal conscious experience is some kind of heavily filtered-down version-

    10. CWChris Williamson1:10:19

        Yeah.

    11. ASAnil Seth1:10:19

        ... of reality.

    12. CWChris Williamson1:10:19

        This is the perturbed version of... the molested, perverse version of what is true. It... it always... it always happens to be that what is true involves psychedelics, you know? It's never what is true is your mind when you're sat on the toilet. Like, that's... it's never that state. It's always a state of sort of psychedelic bliss.

    13. ASAnil Seth1:10:38

        Yeah. And... and... and... and that's... I mean, that's one way you can go, and you can say, "Now I've seen things as they really are. The blinkers are off. The filters have been s-... have been removed." That, for me, is not an appealing way to think about it. It is for me... it is, yeah, you... you change a brain, you change your experience. It's exactly what you would expect to happen if our conscious experiences were embodied biological phenomena.

13. 1:11:04 – 1:15:58

    How Anil’s Studies Have Impacted His Outlook

    1. ASAnil Seth1:11:04

    2. CWChris Williamson1:11:04

       Moving beyond just your research, how has all of the work that you've done into the nature of self changed about how you think about problems or deal with the... the challenges and the joys of life? Have you found that it's sort of impacted, uh, the... the way that you relate to emotions? Because one of the things we haven't necessarily mentioned is-

    3. ASAnil Seth1:11:24

       Mm-hmm.

    4. CWChris Williamson1:11:25

       ... emotions, for all that they may be this phenomenon that exist and they're kind of... they're... o- o- o-... they're and not there at the same time, they feel incredibly real. They feel like the most real thing that you can think of. You know, going through anxiety, it's... it's the reason why, uh, the Greeks and the Romans personified the gods, right? Because it felt like something... it... it was such a visceral experience that it could only be bestowed on you by a higher power that was cursing or blessing you specifically. And I'm... I'm interested in how all of this time thinking about the nature of self and consciousness has changed your relationship with your enjoyable and unenjoyable experience of it.

    5. ASAnil Seth1:12:07

       Yeah. Emotions, they're... they're (laughs) definitely real as experiences and they're probably the most important experiences we have. I mean, they... they're what matters and they guide and direct our behavior every minute of every day. They're real in... in the same way that colors are real, I think. They... they don't exist out there independently of a mind, but they are critical to our mental lives. In my work, I've... think of that connection even more tightly. So, an emotion, for me, is another kind of perception. It's a perception of the state of the body in the context in which we're in. It's a perceptual inference about what's happening in the body, and so they're very tightly coupled. And thinking about this a lot, it's always a challenging question to try and understand what its impact has been on me personally, partly because I don't have a twin brother who went off to be, uh, an estate agent to compare against, but I think it has had an effect, however unreliable that introspective conclusion might be, and I mean, I can kind of see it. Maybe it's just getting older as well, but I can kind of...... see that I'm a bit more adaptively detached from the transient flow of emotions than I was. Not entirely. I mean, I'm not trying to, I'm not claiming to be some sort of enlightened, um, monk. I mean, I still feel frustrated, anxious, sad, upset, frus- furious at times, happy too sometimes. No, the, the flow of emotions is still there, but I think it has helped me in the round to navigate things more effectively. And of course, one, you... The goal isn't to be uniformly happy, I don't think. The goal is to just be able to, um, accept the stream of emotions and curate them a little bit, but to, to live a life where they're part of you and you don't try and fight them quite so much. I think in one specific area I can see progress. So for... A few times in my life I did suffer depression and I had it pretty bad and, and, and when you were saying that the visceral reality of things like anxiety, I, I know this very well. And these were, you know, the hardest times in my life. How to get out of those is, you know, it's a great challenge, everyone does it in their own way, but I think thinking about the impermanence, the constructed provisional nature of the self and of emotional responses has helped me in this regard a bit. It provides a little bit of a psychological immune system. It may be a bit similar to, to meditation. You know, people who've done a ton of meditation also learn to pay attention to their emotions and their mental states and to recognize that they're transient, that they pass. I think the direct experience of meditation is probably better than the theoretical knowledge, you know, in the same way that direct experience of psychedelics exceeds and outstrips what one might learn from the books and from experiments. But I think it can get you somewhere. And, in a sense, thinking about consciousness for now, 20, 25, 30 years, that's been a lot of hours. And so in a way that's been a lot of some kind of meditative practice on the nature of the self and of perception. And I would be, I'd be disappointed if it had no effect. I think it has had an effect, and I think it's had a beneficial effect though, you know, there's still a lot of work (laughs) . I'm still very much a work in progress.

    6. CWChris Williamson1:15:57

       Anil Seth,

14. 1:15:58 – 1:16:35

    Where to Find Anil

    1. CWChris Williamson1:15:58

       ladies and gentlemen. If people want to keep up to date with the stuff that you're doing online, where should they go?

    2. ASAnil Seth1:16:02

       The easiest place, go to my website. It's anilseth.com or you can follow me on Twitter, I still use Twitter, anilkseth.

    3. CWChris Williamson1:16:11

       Anil, I really appreciate you. Uh, I look forward to seeing what you do next. I've been a fan of your work for a long time, so it's been very cool to catch up today.

    4. ASAnil Seth1:16:18

       I'm so glad we were able to have this conversation. I know it took a long time to arrange. Thanks so much, Chris.

    5. CWChris Williamson1:16:23

       What's happening people? Thank you very much for tuning in. If you enjoyed that episode, then press here for a selection of the best clips from the podcast over the last few weeks. And don't forget to subscribe.

Episode duration: 1:16:35